The present invention relates generally to wireless communication devices and methods. More particularly, this method relates to an enhanced sleep mode operation for a broadband wireless communication system.
Wireless communication systems are being developed to permit high speed, wireless communication of data from point to point in a network. For such a system, an air interface standard defines transmission formats and timing to permit reliable communication between transmitters and receivers. Other features and capabilities may be added by the air interface as well. The transmitters and receivers may be stand-alone devices such as mobile telephones or may be incorporated with other devices such as computers or routers.
One example of such a system is known as Worldwide Interoperability for Microwave Access, or WiMAX™ referred to herein after as WiMAX. WiMAX is defined according to standards published by the Institute of Electrical and Electronics Engineers (IEEE) which are generally referred to as IEEE 802.16. One version of the standard, generally referred to as 802.16e, sets forth requirements with respect to access by both fixed and mobile devices. In a WiMAX system, a subscriber station can communicate by radio with one or more base stations (BS). Each BS provides communication services to subscriber stations in a service area near the BS. In a WiMAX system, communication can be point to point or point to multipoint, and a subscriber station can have multiple active or inactive connections to other radios in the system.
A key feature required for use by a mobile device is a low power sleep mode. Mobile devices are powered by rechargeable batteries, and minimization of power consumption is a key design feature. When a mobile device is not transmitting or receiving data in an active mode, the mobile device is able to enter the low power sleep mode to conserve battery power. When the device receives a trigger, it discontinues the sleep mode and resumes normal operation in the active mode.
For entry into sleep mode, a WiMAX mobile device negotiates sleep mode per connection. In the negotiation, the mobile device exchanges sleep duration, awaken duration and sleep start duration with the network. If all connections are in sleep mode, the subscriber station can start low power mode operation. The subscriber station exits the low power operation if it receives any one of (1) a wake up message, or mobile traffic indication message, which indicates the system has data to transmit to the subscriber station; (2) data traffic on the connection identifier (CID) which is in sleep mode; or (3) data traffic from a host interface which uses the subscriber station to communicate with the WiMAX network.
While sleep mode operation has been successful in reducing battery power consumption and extending the operating life of mobile devices, it would be desirable to provide for an improved method and apparatus for controlling sleep mode operation in a wireless communication system such as a WiMAX network.